Someone thinks the Main Character of a story is the person who experiences the most tension:
Another way of distinguishing a movie's central figure is to determine which character is encountering the greatest amount of tension....William Wallace's tension is external. That is, things are done to him by others. But in spite of all this, he has little internal tension. Internal tension is the wondering, "What do I do now?" William Wallace has grief, sorrow, anger and frustration. But these are not the type of tension that makes movie characters most memorable and most empathetic for viewers.
This is the problem with screenwriting paradigms like the Sequence Method. They erroneously try to identify the structure of a story from the Audience's point-of-view--something that is impossible to do and overflowing with subjective misinterpretations. Asking "dramatic questions" is the surest way to completely confuse yourself as to how a story actually works.
The Main Character
The Main Character of a story is the character who offers us a personal point-of-view into the story. We identify with them because we share their problems with them. By assuming their position we experience the story's overarching problem both from within and without.
That is what separates a story from everything else.
If a character does something off-screen that we don't see or hear about until later, we are not seeing that character from their point-of-view. This is why Red is the Main Character in Shawshank and why the men in the barracks are the Main Character of Stalag 17, not William Holden.
If we were Andy in Shawshank or Robert the Bruce in Braveheart we would not be surprised by the hole in the wall or the betrayal. We can't be surprised by our own actions.
The Influence Character
William Wallace absolutely struggles with internal tension--we only see it externalized. His struggle is to maintain his point-of-view and remain steadfast against everyone who thinks differently than him.
There once was a director at Dreamworks who was convinced Po wasn't the Main Character of Kung Fu Panda because he didn't change. Po did change--he grew into his resolve. Yes Shifu, the Dustin Hoffman character, had the biggest paradigm shift but we were always in Po's personal point-of-view.
This error in judgment led to many broken stories.
Shifu and Robert the Bruce both act as Influence Characters towards Po and William Wallace. Their points-of-view challenge their respective Main Characters and force them to grow stronger in their resolve. Their role is to supply the Influence Character Throughline.
What Do I Do Now?
You don't ask dramatic questions.
And so the tension begins. What will Robert do? Will he go against his father's wishes and fight for justice, honor and integrity? Or will he go against what he now knows to be the right thing to do, in order to secure his land, possessions and title? That is internal tension par excellence. "Do I heed the words of my own father, or do I follow the man who has inspired me to do what I now know to be right?"
Unfortunately, the accurate way to pose this question is "Do you heed the words of your own father, or do you follow what I have inspired you to do and what you know to be right." We're never once in Robert's shoes. We are always looking at him from the You perspective--what are you doing? and especially, how could you do that?
Bonus points, though, for identifying Robert's problem--Conscience. His Solution of giving into Temptation inspired by Wallace's sacrifice.